docs: def get_var_by_name(self, name):
          '''
          Look for the named local variable, returning a (PyObjectPtr, scope) pair
          where scope is a string 'local', 'global', 'builtin'
  
          If not found, return (None, None)
          '''
          for pyop_name, pyop_value in self.iter_locals():
              if name == pyop_name.proxyval(set()):
                  return pyop_value, 'local'
          for pyop_name, pyop_value in self.iter_globals():
              if name == pyop_name.proxyval(set()):
                  return pyop_value, 'global'
          for pyop_name, pyop_value in self.iter_builtins():
              if name == pyop_name.proxyval(set()):
                  return pyop_value, 'builtin'
          return None, None